Machines, such as wheel loaders, track loaders, backhoe loaders and the like known in the art, are used for moving material from one place to another at a worksite. These machines include a body portion housing the engine and having rear wheels driven by the engine and an elevated operator environment, such as a cab, for the operator. In wheel loader machines, a front non-engine end frame with the front wheels is attached to the body portion by an articulated connection allowing the end frame to pivot from side-to-side to steer the machine. The end frame may further include linkages, such as Z-bar linkages, for manipulating an implement of the machine. A pair of lift arms coupled to the end frame are raised and lowered by corresponding lift cylinders to adjust the elevation of the implement above the ground. Where Z-bar linkages are used, the tilt of the implement (rotation of the implement about a pivot connection at the end of the lift arms) is controlled by a tilt lever and tilt link coupled between the lift arms and the implement, and driven by a tilt cylinder. An example of a wheel loader machine implementing a Z-bar linkage is provided in U.S. Publication No. 2006/0291987, published Dec. 28, 2006. Other types of machines and other types of linkages having tilt cylinders operatively coupled to their implements are also known in the art.
In known machines having tilt cylinders, an end of the tilt cylinder opposite an end connected to the tilt lever is pivotally connected to the frame by a pair of upwardly extending support plates. The support plates are typically welded to a base plate or mounting plate of the frame at their bottom edges. Support plates are generally parallel to each other and to a longitudinal axis extending from the front to the back of the machine. The plates have circular openings there through, with an end of the tilt cylinder being disposed there between. A pivot pin extends through the openings and the end of the tilt cylinder so that the tilt cylinder to rotate about the pivot pin. The other end of the tilt link is coupled to the implement via the tilt link and tilt lever.
As a tilt cylinder operates to articulate the implement, forces in the direction of the longitudinal axis of the tilt cylinder are generated and act on the pivot pin as shear forces perpendicular to the longitudinal axis of the pivot pin. These forces in turn are transmitted to the support plates in the longitudinal direction of the machine. The support plates oriented as described have sufficient surface contact between the support plates and the base plates in the longitudinal direction to transition the longitudinal loads without failure for the duration of the design life of the support plates.
The longitudinal loads constitute the majority of the loads that are borne by the support plates. However, horizontal loads acting in the direction perpendicular to the longitudinal direction of the machine and parallel to the longitudinal axis of the pivot pin are also applied to the support plates. The horizontal loads may be generated when an unbalanced load is applied to the implement, or when other lateral loads are applied to the implement due to engagement with other objects. These loads are the result of the use of the machines in extreme settings. The typical design of the support plates focuses on the longitudinal structure transition between the support plates and the mounting plate. The horizontal loads and structure transition are considered, but the support plates are relatively thin in the horizontal direction in contrast to the longitudinal direction. This design renders the support plates relatively weak in horizontal transition, and can result in cracking of the support plates or the welds attaching the support plates to the mounting plate due to fatigue caused by the repetitive horizontal loading. Therefore, a need exists for an improved tilt cylinder support structure providing increased resistance to horizontal loading, and a corresponding increase in the useful life of the support structure.